three pipes A, B, and C and fill the tank in 10 hours, 20 hours and 40 hours respectively. In the beginning all of them are opened simultaneously. After 2 hours, tap C is closed and A and B are kept running. After the 4 th hour, tap B is also closed. The remaining work is done by tap A alone. What is the percentage of the work dane by tap A alone?

three pipes A, B, and C and fill the tank in 10 hours, 20 hours and 4

1.	three pipes A, B, and C and fill the tank in 10 hours, 20 hours and 40 hours respectively. In the beginning all of them are opened simultaneously. After 2 hours, tap C is closed and A and B are kept running. After the 4 th hour, tap B is also closed. The remaining work is done by tap A alone. What is the percentage of the work dane by tap A alone?
Answer» `30%` `35%` `45%` `50%` Solution :Pipe A's work in `% = 100/10 = 10%` Pipe B's work in `%= 100/20= 5%` Pipe C's work in `%=100/40 = 2.5 %` All of them are opened for 2 hours + after 2 hours, tap C is closed + After the 4th hour, tap B is also closed =100 `THEREFORE (10 + 5 + 2.5) xx 2 + (10+5) xx 2 + X = 100` ` therefore 35+ 30 +` work by tap A alone` = 100` `therefore` work by tap A alone `= 100 - 65 = 35%`